JP2009016844A - Oxide semiconductor, and thin film transistor having the same and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oxide semiconductor containing Ga<SB>x</SB>In<SB>y</SB>Zn<SB>z</SB>oxide and a new material, and to provide a thin film transistor whose property is improved by adding the Ga<SB>x</SB>In<SB>y</SB>Zn<SB>z</SB>oxide and the new material as the channels of the thin film transistor, and its manufacturing method. <P>SOLUTION: The oxide semiconductor contains the Ga<SB>x</SB>In<SB>y</SB>Zn<SB>z</SB>oxide, and at least one material selected from groups consisting of a 4A-group material, oxide of the 4A-group material and a rare earth material. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an oxide semiconductor and a thin film transistor including the oxide semiconductor, and more particularly to an oxide semiconductor obtained by adding a new substance to a Zn oxide system, a thin film transistor formed using the oxide semiconductor as a channel, and a method for manufacturing the same.

  Currently, a thin film transistor (hereinafter referred to as TFT) is used as a switching and driving element in the display field, and is also used as a selection switch for a cross-point memory element, and is used in various application fields. Yes.

An amorphous silicon thin film transistor (amorphous-silicon TFT: hereinafter referred to as a-Si TFT) is used as a display driving and switching element. This is an element that is uniformly formed on a large substrate of 2 m or more at low cost, and is currently the most widely used element. However, due to the trend toward larger displays and higher image quality, high device performance is required, and it is judged that existing a-Si TFTs with a mobility of 0.5 cm ² / Vs have reached their limits. . Therefore, there is a need for high performance TFTs and manufacturing techniques that have higher mobility than a-Si TFTs.

A polycrystalline silicon thin film transistor (poly-Si TFT) having a very high performance as compared with an a-Si TFT has a high mobility of several tens to several hundreds cm ² / Vs, and thus is an existing a-Si TFT. It has performance that can be applied to high-resolution displays that were difficult to achieve.
In addition, there is very little problem of deterioration of element characteristics as compared with a-Si TFT. However, in order to manufacture the poly-Si TFT, a complicated process is required as compared with the a-Si TFT, and the additional cost is increased accordingly.

  Therefore, the p-Si TFT is suitable for application to a product such as high resolution display and OLED (Organic Light Emitting Diode), but it is inferior to the existing a-Si TFT in terms of cost. There is a disadvantage that the application is limited. In the case of p-Si TFTs, because of technical problems such as limitations on manufacturing facilities and poor uniformity, a manufacturing process using a large substrate of 1 m or more has not been realized so far. There was a problem that the application of was difficult.

Accordingly, there is a demand for new TFT technology having both the advantages of a-Si TFTs and the advantages of poly-Si TFTs. Research on this is actively progressing, and a typical example is an oxide semiconductor element.
ZnO, IZO (InZnO), GIZO (GaInZnO), and the like have been introduced as oxide semiconductor elements that have recently attracted attention.
An oxide semiconductor element can be manufactured at a low temperature and has an advantage that it can be easily enlarged because of an amorphous phase. In addition, an oxide semiconductor film has a high mobility material and has very good electrical characteristics like polycrystalline silicon. Currently, research is being conducted to use an oxide semiconductor material layer with high mobility, that is, an oxide material layer in a channel region of a thin film transistor.

Therefore, the present invention has been made in view of the problems in the above-described conventional semiconductor elements, and an object of the present invention is to provide an oxide semiconductor containing a Ga _x In _y Zn _z oxide and a new substance. It is in.
Another object of the present invention is to provide a thin film transistor including an oxide semiconductor in which a Ga _x In _y Zn _z oxide and a new substance are added as a channel of the thin film transistor to improve the characteristics, and a method for manufacturing the thin film transistor. There is.

An oxide semiconductor according to the present invention made to achieve the above object is an oxide semiconductor, and is composed of a Ga _x In _y Zn _z oxide, a Group 4A material, a Group 4A material oxide, and a rare earth material. It contains at least one substance selected from the group.

The Ga _x In _y Zn _z oxide is doped with at least one material selected from the group consisting of a group 4A material, a group 4A material oxide, and a rare earth material, or the Ga _x In _y Zn It is preferable to include a mixture of at least one material selected from the group consisting of _z oxides, Group 4A materials, Group 4A material oxides, and rare earth materials.
The group 4A material is preferably at least one selected from the group consisting of Ti, Zr, and Hf.
The oxide semiconductor is preferably a TiInZn oxide or a TiGaInZn oxide.
The Ga _x In _y Zn _z oxide includes at least one substance selected from the group consisting of a group 4A material, a group 4A material oxide, and a rare earth material in a range of 0.01 to 10.00 at%. Is preferred.
The oxide semiconductor includes at least one selected from the group consisting of a first oxide layer formed of the Ga _x In _y Zn _z oxide, a group 4A material, a group 4A oxide, and a rare earth material. It is preferable to have a substance layer formed of a substance.

The material layer is preferably formed with a thickness of 5 to 20 nm.
It is preferable to further include a second oxide layer formed on the material layer and containing a Ga _x In _y Zn _z oxide.
The oxide semiconductor preferably has a polycrystalline structure or a nanocrystalline structure.
The oxide semiconductor preferably has a polycrystalline structure or a mixed phase of a nanocrystalline structure and an amorphous structure.
In the Ga _x In _y Zn _z oxide, x, y, and z represent an atomic ratio, and satisfy at least one of x + y + z = 1, x + y = 1, x + z = 1, y + z = 1, and z = 1. It is preferable.

The thin film transistor according to the present invention, which has been made to achieve the above object, is a thin film transistor formed at a gate and a position corresponding to the gate, and is oxidized into a Ga _x In _y Zn _z oxide with a 4A group material and a 4A group material oxidized. And a channel including at least one material selected from the group consisting of a rare earth material, a gate insulator formed between the gate and the channel, and both sides of the channel. It has a source and a drain.

A method of manufacturing a thin film transistor according to the present invention made to achieve the above object is a method of manufacturing a thin film transistor, the step of forming a gate and a gate insulating layer on the gate, and the gate at a position corresponding to the gate. Forming a channel containing at least one material selected from the group consisting of a group 4A material, a group 4A material oxide, and a rare earth material on a Ga _x In _y Zn _z oxide on an insulating layer; And a step of forming a source and a drain which are respectively in contact with the portion.

The _channels, Ga x _In y Zn _z 4A Group material oxide, 4A Group material oxides, and sputtering at least one material selected from the group consisting of a rare earth material, CVD, ALD (Atomic Layer Deposition ), laser Preferably, it is formed by doping by at least one method selected from the group consisting of vapor deposition method, ion implantation, and ion shower.
The _channels, Ga x _In y Zn _z oxide 4A group substances, group 4A material oxide, and after depositing at least one material selected from the group consisting of a rare earth material, the heat-treated _Ga x an In _y It is preferably formed by diffusing in the _Znz oxide.
The step of forming the channel is at least selected from the group consisting of a step of forming a first oxide layer with a Ga _x In _y Zn _z oxide, a group 4A material, a group 4A material oxide, and a rare earth material. And forming a material layer with one material.
The material layer is preferably formed with a thickness of 5 to 20 nm.

The step of forming the channel preferably includes a step of further forming a second oxide layer including a Ga _x In _y Zn _z oxide on the material layer.
After the formation of the source and drain, it is preferable to further include a step of performing heat treatment using a heating furnace, RTA (Rapid Thermal Annealing), laser, hot plate or the like at a temperature of 100 to 450 ° C.
In the Ga _x In _y Zn _z oxide, x, y, and z represent an atomic ratio, and satisfy at least one of x + y + z = 1, x + y = 1, x + z = 1, y + z = 1, and z = 1. It is preferable.

According to the oxide semiconductor, the thin film transistor including the oxide semiconductor, and the manufacturing method thereof according to the present invention, by forming a channel of a single layer or a multilayer structure with a new substance in a Ga _x In _y Zn _z oxide, mobility, etc. There is an effect that a Ga _x In _y Zn _z oxide thin film transistor having improved electrical characteristics can be provided.

  Next, specific examples of the best mode for carrying out an oxide semiconductor according to the present invention, a thin film transistor having the oxide semiconductor, and a method for manufacturing the same will be described with reference to the drawings.

  Here, it should be understood that the thickness and width of each layer shown in the drawings are expressed with some exaggeration for the purpose of explanation.

FIG. 1 is a cross-sectional view illustrating a structure of a thin film transistor including an oxide semiconductor according to an embodiment of the present invention.
Although only the bottom gate type thin film transistor is shown in FIG. 1, the thin film transistor according to the embodiment of the present invention can be either a top gate type or a bottom gate type thin film transistor.

Referring to FIG. 1, a thin film transistor according to an embodiment of the present invention is formed on a substrate 11 having an insulating layer 12 formed on a surface thereof, a gate 13 formed on a region of the substrate 11, a substrate 11 and the gate 13. The gate insulating layer 14 is formed on the gate insulating layer 14 at a position corresponding to the gate 13 and is selected from the group consisting of an oxide of a 4A group material, an oxide of a 4A group material, and a rare earth material as a Ga _x In _y Zn _z oxide. The channel 15 includes at least one material, and the source 16 a and the drain 16 b are formed on both sides of the channel 15.

The materials of each layer forming the thin film transistor according to the embodiment of the present invention will be described as follows.
As the substrate 11, a substrate used for a semiconductor element can be used. For example, silicon, glass, plastic, or an organic material can be used. When the substrate 11 is formed of silicon, the insulating layer 12 can be formed by forming a SiO ₂ thermally oxidized material on the surface of the substrate 11 by a thermal oxidation process or the like.

The gate 13 can be formed of a conductive material, and can be used of a metal or a conductive metal oxide. The gate insulating layer 14 can be formed using an insulating material used for a semiconductor device, and silicon oxide or nitride can be used. _{Specifically, HfO 2, Al 2 O 3} , Si 3 N 4 having a high dielectric constant than SiO ₂ or SiO ₂ High-K material, or a mixture thereof can be used.
The source 16a and the drain 16b can be formed using a conductive material, for example, a metal such as Cr, Pt, Ru, Au, Ag, Mo, Al, W, Cu, AlNd, or ITO, GIZO, GZO. A metal such as AZO, IZO (InZnO), AZO (AlZnO), or a conductive oxide can be used.

In the thin film transistor according to the embodiment of the present invention, the channel 15 is an oxide containing at least one material selected from the group consisting of a Group 4A material, a Group 4A material oxide, and a rare earth material in a Ga _x In _y Zn _z oxide. It is formed by a physical semiconductor.
_{Examples of the} Ga _x In _y Zn _z oxide include GaIn oxide, InZn oxide, GaInZn oxide, and Zn oxide. Here, x, y, and z represent atomic ratios, and satisfy at least one of x + y + z = 1, x + y = 1, x + z = 1, y + z = 1, and z = 1.

Examples of Group 4A materials include Ti, Zr, Hf, and mixtures thereof. The rare earth includes Yi, La, Pr, Nd, Dy, Ce, Y, Tb, Gd, Er, Yb, and mixtures thereof. The channel 15 has a structure in which at least one material selected from the group consisting of a group 4A material, a group 4A material oxide, and a rare earth material is doped in an oxide semiconductor, or a Ga _x In _y Zn _z oxidation. And a mixture structure of at least one material selected from the group consisting of a material, a group 4A material, a group 4A material oxide, and a rare earth material.

  In this case, 0.01 to 10.00 at% of a 4A group material, a 4A group oxide, or a rare earth material is added to the Zn oxide. The channel is formed in a thickness range of 200 nm or less.

The channel 15 is at least one material selected from the group consisting of a first oxide layer formed of a Ga _x In _y Zn _z oxide, a Group 4A material, a Group 4A material oxide, and a rare earth material. A multilayer structure including the formed material layer may also be used. In addition, a second oxide layer including a Ga _x In _y Zn _z oxide may be selectively formed on the material layer, and the first oxide layer and the material layer may be alternately formed. Therefore, the first oxide layer and the second oxide layer may include the same or different Ga _x In _y Zn _z oxide.

Next, a method of manufacturing a thin film transistor according to an embodiment of the present invention will be described in detail with reference to FIGS.
Referring to FIG. 2, first, a substrate 11 is prepared, and then an insulating layer 12 is formed on the surface of the substrate 11. Next, a conductive material 13a such as metal or conductive metal oxide is formed on the substrate 11 by vapor deposition or the like. The substrate 11 can be formed using silicon, glass, or an organic material. When the substrate 11 is formed of silicon, the insulating layer 12 can be formed on the surface of the substrate 11 by a thermal oxidation process.

Referring to FIG. 3, a gate 13 is formed by patterning a conductive material 13a. Referring to FIG. 4, an insulating material such as HfO ₂ , Al ₂ O ₃ , Si ₃ N ₄ , or a mixture thereof having a higher dielectric constant than SiO ₂ or SiO ₂ is formed on the gate 13. The gate insulating layer 14 is formed by forming and patterning by vapor deposition or the like.

  Referring to FIG. 5, after forming a channel material on the gate insulating layer 14 by vapor deposition or the like, the channel 15 is formed by patterning so that the channel material in the region corresponding to the gate 13 remains. Here, the step of forming the channel 15 with an oxide semiconductor will be described in detail as follows.

For example, a process of forming the channel 15 by sputtering will be described.
At least one material target selected from the group consisting of a Ga _x In _y Zn _z oxide target, a Group 4A material, a Group 4A material oxide, and a rare earth material is mounted in the process chamber, and then Ga _x In _y Zn. _At least one material selected from the group consisting of a _z oxide, a group 4A material, a group 4A material oxide, and a rare earth material is formed on the gate insulating layer 14.

For the formation of the Ga _x In _y Zn _z oxide, both DC (direct current) sputtering and RF (radio frequency) sputtering can be used.
When using Ga _x In _y Zn _z DC to the formation of oxide (direct current) sputtering _method, materials used for forming the Ga x _In y Zn _z oxide may be added simultaneously. Further, when an RF (radio frequency) sputtering method is used to form a Ga _x In _y Zn _z oxide, sputtering can be performed on an oxide such as TiO ₂ . At this time, the power of the sputtering gun is adjusted in order to adjust the amount of the 4A group material, 4A group oxide or rare earth material contained in the Ga _x In _y Zn _z oxide. The gas partial pressures of the inert gas and the oxygen gas in the chamber can be controlled by adjusting the amount of oxygen.

As a process of injecting a Group 4A material, Group 4A material oxide or rare earth material into the channel, sputtering, CVD (Chemical Vapor Deposition), ALD (Atomic Layer Deposition), laser deposition, ion implantation or ion shower, etc. Process can be used. In addition, after depositing at least one material selected from the group consisting of a group 4A material, a group 4A material oxide, and a rare earth material on a Ga _x In _y Zn _z oxide, heat treatment such as thermal annealing or laser annealing is performed. Thus, the channel can be formed by diffusing into the Ga _x In _y Zn _z oxide. When Ti is added, TiInZn oxide or TiGaInZn oxide is formed.

In the case of forming the channel 15 having a multilayer structure, a Ga _x In _y Zn _z oxide is first formed on the gate insulating layer 14 by vapor deposition or the like, and an oxide of a 4A group material, a 4A group material, and a rare earth are formed thereon. At least one substance selected from the group consisting of substances is formed by vapor deposition or the like. Here, a Ga _x In _y Zn _z oxide can be selectively formed thereon by vapor deposition or the like.
FIG. 9 shows the result of SIMS analysis after forming channel 15 by adding Ti to GaInZn oxide (GIZO) with sputtering power of about 30 and 50 W. FIG.

  Referring to FIG. 6, after the channel 15 is formed, a material such as a metal or a conductive metal oxide is formed on the channel 15 and the gate insulating layer 14 by vapor deposition or the like, and the upper portion of the channel 15 is patterned to form both sides of the channel 15. A source 16a and a drain 16b connected to the part are formed.

  Finally, a heat treatment process is performed on the channel at 100 to 450 ° C. using a furnace, RTA (Rapid Thermal Annealing), laser or hot plate.

When the channel 15 is formed by doping Zn oxide with at least one material selected from the group consisting of Group 4A material, Group 4A material oxide, and rare earth material, the channel 15 may be polycrystalline or nanocrystalline. The structure may be included, or a mixed structure of a polycrystalline or nanocrystalline structure and an amorphous phase may be included.
When the channel 15 has a single layer structure, a nanocrystal or microcrystal crystal phase is generated in the channel 15, and when a channel 15 having a multilayer structure is formed, a polycrystal crystal phase can be generated in the channel 15.

  FIG. 7 is a graph showing electrical characteristics of the thin film transistor according to the related art and the embodiment of the present invention, and is a graph showing a change in gate voltage (Vg) −drain current (Id). G31 is a thin film transistor that is formed by GIZO without adding a separate substance and then heat-treated at 350 ° C., and G32 is formed at 400 ° C. after forming the channel under the conditions of GIZO 200 W (sputter power) and Ti 30 W. A thin film transistor formed by heat treatment, and G33 is a thin film transistor formed by forming a channel under the conditions of GIZO 200W (sputtering power) and Ti 30W and then performing heat treatment at 350 ° C.

Referring to FIG. 7, it can be seen that the On current is about 10 ⁻⁵ A, the off current is 10 ⁻¹³ A or less, and the On / Off current ratio is 10 ⁸ or more. It can be seen that the electrical characteristics of any of the thin film transistors G31, G32, and G33 are satisfactory for use as a thin film transistor.

  FIG. 8 is a graph showing mobility characteristics of a thin film transistor according to an embodiment of the prior art and the present invention. G41 is a thin film transistor formed by GIZO without forming a separate material and then heat-treated at 350 ° C., and G42, G43, and G44 are formed under the conditions of GIZO 200W (sputter power) and Ti 30W. Then, the thin film transistors formed by heat treatment at 350 ° C., 400 ° C., and 450 ° C., respectively.

  Referring to FIG. 8, it can be seen that the mobility of G42 and G43 is improved about twice as compared with the thin film transistor G41 according to the prior art. However, in the case of the thin film transistor G44 heat-treated at 450 ° C., it can be seen that the mobility is reduced compared to the thin film transistor G41 according to the prior art. Therefore, it can be seen that heat treatment at a temperature lower than 450 ° C. is advantageous for improving the device characteristics.

  Through the above embodiments, those skilled in the art will be able to manufacture various electronic devices such as a display or a cross-point type memory device using the oxide thin film transistor according to the technical idea of the present invention. The oxide thin film transistor according to an embodiment of the present invention may be used in a bottom gate type or a top gate type.

  The present invention is not limited to the embodiment described above. Various modifications can be made without departing from the technical scope of the present invention.

  The present invention can be applied to a display using an oxide semiconductor and a thin film transistor including the oxide semiconductor, a cross-point memory element, or the like.

It is sectional drawing which shows the thin-film transistor containing the oxide semiconductor by embodiment of this invention. It is sectional drawing for demonstrating the manufacturing method of the thin-film transistor by embodiment of this invention. It is sectional drawing for demonstrating the manufacturing method of the thin-film transistor by embodiment of this invention. It is sectional drawing for demonstrating the manufacturing method of the thin-film transistor by embodiment of this invention. It is sectional drawing for demonstrating the manufacturing method of the thin-film transistor by embodiment of this invention. It is sectional drawing for demonstrating the manufacturing method of the thin-film transistor by embodiment of this invention. 4 is a graph showing electrical characteristics of a thin film transistor according to an embodiment of the prior art and the present invention, and is a graph showing a change in gate voltage (Vg) −drain current (Id). 5 is a graph illustrating mobility characteristics of a thin film transistor according to an embodiment of the prior art and the present invention. It is a graph which shows the result analyzed by SIMS, after adding Ti to GIZO with the sputtering power of about 30 and 50 W and forming a channel.

Explanation of symbols

11 Substrate 12 Insulating layer 13 Gate 14 Gate insulating layer 15 Channel 16a Source 16b Drain

Claims (30)

An oxide semiconductor,
An oxide semiconductor, wherein the Ga _x In _y Zn _z oxide includes at least one material selected from the group consisting of a group 4A material, a group 4A material oxide, and a rare earth material. The Ga _x In _y Zn _z oxide is doped with at least one material selected from the group consisting of a group 4A material, a group 4A material oxide, and a rare earth material, or the Ga _x In _y Zn _2. The oxide semiconductor according to claim 1, comprising a mixture of at least one material selected from the group consisting of a _z oxide, a group 4A material, a group 4A material oxide, and a rare earth material.   3. The oxide semiconductor according to claim 2, wherein the 4A group material is at least one selected from the group consisting of Ti, Zr, and Hf.   The oxide semiconductor according to claim 3, wherein the oxide semiconductor is a TiInZn oxide or a TiGaInZn oxide. The Ga _x In _y Zn _z oxide includes at least one substance selected from the group consisting of a group 4A material, a group 4A material oxide, and a rare earth material in a range of 0.01 to 10.00 at%. The oxide semiconductor according to claim 1. The oxide semiconductor includes a first oxide layer formed of the Ga _x In _y Zn _z oxide,
2. The oxide according to claim 1, comprising a material layer formed of at least one material selected from the group consisting of a group 4A material, a group 4A material oxide, and a rare earth material. semiconductor.   The oxide semiconductor according to claim 6, wherein the material layer is formed with a thickness of 5 to 20 nm. The oxide semiconductor according to claim 6, further comprising a second oxide layer formed on the material layer and containing a Ga _x In _y Zn _z oxide.   The oxide semiconductor according to claim 1, wherein the oxide semiconductor has a polycrystalline structure or a nanocrystalline structure.   The oxide semiconductor according to claim 1, wherein the oxide semiconductor has a polycrystalline structure or a mixed phase of a nanocrystalline structure and an amorphous structure. In the Ga _x In _y Zn _z oxide, x, y, and z represent an atomic ratio, and satisfy at least one of x + y + z = 1, x + y = 1, x + z = 1, y + z = 1, and z = 1. The oxide semiconductor according to claim 1. A thin film transistor,
The gate,
A channel formed at a position corresponding to the gate and including at least one material selected from the group consisting of a Group 4A material, a Group 4A material oxide, and a rare earth material in a Ga _x In _y Zn _z oxide;
A gate insulator formed between the gate and the channel;
A thin film transistor comprising a source and a drain formed in contact with both sides of the channel. The channel has a structure in which at least one material selected from the group consisting of a group 4A material, a group 4A material oxide, and a rare earth material is doped in the Ga _x In _y Zn _z oxide, or the Ga _x In _y Zn _z oxide and 4A group substance, group 4A material oxide, and a thin film transistor according to claim 12, characterized in that it comprises a mixture of at least one material selected from the group consisting of a rare earth material.   The thin film transistor of claim 13, wherein the group 4A material is at least one selected from the group consisting of Ti, Zr, and Hf.   The thin film transistor according to claim 14, wherein the channel is a TiInZn oxide or a TiGaInZn oxide. The channel, the _Ga x _In y Zn _z 4A Group material oxides within, 4A Group material oxide, and a range of at least one material selected from the group consisting of rare earth material is 0.01～10.00At% The thin film transistor according to claim 12, wherein the thin film transistor is included. The channel includes a first oxide layer formed of Ga _x In _y Zn _z oxide;
13. The thin film transistor according to claim 12, further comprising: a material layer formed of at least one material selected from the group consisting of a group 4A material, a group 4A material oxide, and a rare earth material.   The thin film transistor of claim 17, wherein the material layer has a thickness of 5 to 20 nm. The channel is formed on material layer, a thin film transistor according to claim 17, further comprising a second oxide layer comprising Ga _x In _y Zn _z oxide.   The thin film transistor of claim 12, wherein the channel has a polycrystalline structure or a nanocrystalline structure.   The thin film transistor of claim 12, wherein the channel has a polycrystalline structure or a mixed phase of a nanocrystalline structure and an amorphous structure. In the Ga _x In _y Zn _z oxide, x, y, and z represent an atomic ratio, and satisfy at least one of x + y + z = 1, x + y = 1, x + z = 1, y + z = 1, and z = 1. The thin film transistor according to claim 12. A method for manufacturing a thin film transistor, comprising:
Forming a gate and a gate insulating layer on the gate;
A channel containing at least one material selected from the group consisting of a Group 4A material, a Group 4A material oxide, and a rare earth material in a Ga _x In _y Zn _z oxide on the gate insulating layer at a position corresponding to the gate. Forming, and
Forming a source and a drain which are in contact with both side portions of the channel, respectively. The _channels, Ga x _In y Zn _z 4A Group material oxide, 4A Group material oxides, and sputtering at least one material selected from the group consisting of a rare earth material, CVD, ALD (Atomic Layer Deposition ), laser 24. The method of manufacturing a thin film transistor according to claim 23, wherein the thin film transistor is formed by doping by at least one method selected from the group consisting of vapor deposition method, ion implantation, and ion shower. The _channels, Ga x _In y Zn _z oxide 4A group substances, group 4A material oxide, and after depositing at least one material selected from the group consisting of a rare earth material, the heat-treated _Ga x an In _y 24. The method of manufacturing a thin film transistor according to claim 23, wherein the thin film transistor is formed by diffusing in a _Znz oxide. Forming the channel comprises forming a first oxide layer of Ga _x In _y Zn _z oxide;
24. The method of manufacturing a thin film transistor according to claim 23, further comprising: forming a material layer with at least one material selected from the group consisting of a group 4A material, a group 4A oxide, and a rare earth material. .   27. The method of claim 26, wherein the material layer is formed with a thickness of 5 to 20 nm. The method for manufacturing a thin film transistor according to claim 26, characterized in that it comprises a step of further forming a second oxide layer comprising Ga _x In _y Zn _z oxide on said material layer forming the channel .   The method further comprises a step of performing heat treatment using a heating furnace, a RTA (Rapid Thermal Annealing), a laser, a hot plate, or the like at a temperature of 100 to 450 ° C. after forming the source and drain. 24. A method for producing the thin film transistor according to 23. In the Ga _x In _y Zn _z oxide, x, y, and z represent an atomic ratio, and satisfy at least one of x + y + z = 1, x + y = 1, x + z = 1, y + z = 1, and z = 1. 24. The method of manufacturing a thin film transistor according to claim 23.

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